Tamper-evident tab thermoformed packaging

ABSTRACT

A package having a lid seated on a base where the edge of the seated lid is generally inaccessible due to contours in the base, and where the edge is made accessible by a tamper-evident tab arrangement. The base includes a tamper-evident tab and a fixed tab disposed on a flange extending about the base. The tamper-evident tab is joined to the base on opposite ends by a breakable land and a permanent land. The tamper-evident tab is movable by breaking the tamper-evident tab free from the base on one end by breaking the breakable land and bending the tamper-evident tab out of the way about the permanent land to provide access to the peripheral edge of the lid. The tamper-evident tab may include an extension adjacent to the breakable land and the fixed tab may include an extension adjacent to the tamper-evident tab extension opposite the breakable land.

BACKGROUND OF THE INVENTION

The present invention relates to packaging and more particularly to tamper-evident thermoformed packaging.

Thermoformed packaging is used in a wide variety of application. The design and construction of thermoformed packaging typically varies from application to application. One common application for thermoformed packaging is food packaging. For example, fruits and vegetables are now commonly sold in containers made from thermoformed parts. Although food packages may vary in design and construction, one type of common food package includes a thermoformed base and a thermoformed lid that can be closed to cooperatively define an article-receiving space. In some applications, the base and lid are formed from a single portion of thermoplastic material and are joined together along a living hinge. In other applications, the base and lid are separately formed.

The base and lid can be secured together using a variety of different options. For example, the base and lid can be permanently sealed (e.g. welded) together to make it difficult to open and therefore tamper with the content of the package. However, permanently sealed packaging has a number of disadvantages. For example, permanently sealing the package can increase the cost of packaging because it may require the use of relatively expensive sealing equipment (e.g. a welder). Further, consumers have increasingly expressed resistance to the use of permanently sealed thermoformed packaging. Permanently sealed packages can be difficult to open, thereby providing a source of frustration for consumers. As a result of these (and perhaps other) disadvantages, there has been an effort to develop alternative packaging constructions that are not welded or otherwise permanently sealed. Some alternative constructions currently in use include a base and a lid that are snap-fitted together, and can therefore be relatively easily opened and closed.

With food packaging (and some other applications), it can be desirable to provide a mechanism that allows a consumer to determine whether or not the package has been opened. With welded or otherwise permanently-sealed packages, the process of opening the package will typically leave an obvious visual indication that the package has been opened. With other types of packages, such as snap-locked packaging, special accommodations may be needed to provide a visual indication when desired. For example, some conventional food packages include a tear strip that must be removed from a package before it can be opened. Removal of the tear strip leaves an unmistakable visual indication that the package has been opened. Tear strips provide some advantages, but they can increase the overall cost of the package, as well as present difficulties during use.

Other types of tamper-evident packaging include a container having a lid that is fitted onto a base. The base includes a peripheral rail that surrounds and is closely aligned with the peripheral edge of the lid. The rail prevents easy access to the edge of the lid and thereby makes it difficult to remove the lid from the base. To obtain access to the edge of the lid, a portion of the base containing a section of the rail is capable of being folded down away from the edge of the lid. In this type of container, the movable portion of the base is joined to the remainder of the base along a hinge disposed at its inner-most edge. In use, the movable portion is folded down along the hinge. Although this configuration has some benefits, the movable portion of the base provides only limited access to the edge of the lid when folded down. This can make it difficult to grasp the edge of the lid and open the container. Further, even after opening it can be difficult to recognize that the container has been tampered with. This is caused in part by the fact that the folded movable portion does not provide the container with sufficient visual discontinuity. The problem can be compounded when, after the movable portion has been bent down, the hinge attempts to return to its original shape, thereby pulling the movable portion back into closer alignment with the peripheral edge of the lid.

SUMMARY OF THE INVENTION

The present invention provides a package having a lid seated on a base where the edge of the seated lid is generally inaccessible due to contours in the base, and where the edge is made accessible by breaking away a portion of the based. In one embodiment, the base includes a tamper-evident tab that is joined to the base on opposite ends and is movable by breaking the tamper-evident tab free from the base on one end. This allows the tab to be bent out of the way to provide access to the edge of the lid. The tamper-evident tab is configured to overlay a significant portion of flange so that, once the tab is moved, a significant portion of the flange is accessible in the region previously occupied by the tab.

In one embodiment, the tab is secured to the base at opposite ends by small lands of material that are generally sufficient to hold the tab in place until the tab is intentionally broken away by a user. The tab may be secured to base at one end by a breakable land and at the opposite end by a permanent land. The permanent land may be substantially greater in width than the breakable land so that substantially greater force is required to break the permanent land. For example, the permanent land may be 1.5, 2 or 3 times the width of the breakable land. In use, access to the edge of the lid may be obtained by rupturing the breakable land and bending the tab out of the way about the permanent land. In this way, the tab remains secured to the base so that there is no waste material that needs to be discarded. The tamper-evident tab may include an extension adjacent to the breakable land and the fixed tab may include an extension adjacent to the tamper-evident tab extension opposite the breakable land. The tamper-evident tab extension and fixed tab extension may each be positioned immediately adjacent to the breakable land.

In one embodiment, the lid is generally circular and the base defines a generally circular opening that is selectively close by the lid. The base may include a generally circular shoulder that receives the lid. The shoulder made include a circumferential rail having an inner circumference only slightly larger than the outer circumference of the lid, whereby the rail impedes access to the peripheral edge of the lid. In one embodiment, the tab includes a portion of the shoulder and the rail.

In one embodiment, the lid and the base are shaped so that the lid is snap-fitted into a seated position on the base over the opening. The base may include a shoulder that forms an undercut configured to receive a corresponding shoulder extending from the lid. In one embodiment, the undercut extends circumferentially around the opening. In one embodiment, the lid shoulder extends circumferentially round the lid.

In one embodiment, the package is generally rectangular with a generally rectangular base and a generally rectangular lid. The tamper-evident tab may be located in a corner of the base. The corner may be somewhat inset to provide additional space for the tamper-evident tab. The inset allows the package to include a relatively large tamper-evident tab arrangement.

In one embodiment, the generally rectangular package may include somewhat convex walls that curve outwardly toward the middle causing the package corners to be inset from the outermost extents of the walls. In such embodiments, the tamper-evident tab may extend beyond the length and width of the package as defined by the outermost extents of the walls. The walls of one package may be curved enough so that even if the tamper-evident tab of an adjacent package extends beyond the length and width of the adjacent package, the corner is inset enough to accommodate the extra length and width occupied by the tab of an adjacent package. In use, this allows each package to include a tamper-evident tab that exceeds the length and width of the package without reduce the number of packages that can be placed on a shelf.

In one embodiment, a fixed tab is disposed immediately adjacent to the movable tamper-evident tab. The fixed tab may provide a structure for holding the package with one hand while the other hand is used to break free and bend down the tamper-evident tab. The tamper-evident tab may include an extension adjacent to the breakable land and the fixed tab may include an extension adjacent to the tamper-evident tab extension opposite the breakable land.

The present invention provides a simple and effective tamper-evident tab arrangement that can be readily integrated into a wide range of thermoformed packages. The tab is disposed so that its removal exposes a significant portion of the edge of the lid so that the lid can be easily gripped from above and below and then lifted to separate the lid from the base. The tab may be oriented so that once opened it provides a high degree of visual discontinuity making it obvious that the tab has been opened or otherwise subject to tampering. The tab may include a permanent land that keeps it firmly secured to the base, thereby eliminated waste that would otherwise need to be discarded. The present invention may be implemented in a package with a circular lid. In circular implementations, the lid can be installed on the base in essentially any rotational position, thereby eliminating any need to utilize manufacturing equipment configured to provide rotational alignment between the lid and the base. The present invention may be implemented in a generally rectangular package. In generally rectangular packages, the corner containing the tamper-evident tab may be inset so that the protruding tab does not increase or provides a limited increase in the overall dimensions of the package. The rectangular package may include somewhat convex walls that allow the tamper-evident tab of another container to exceed the length and width of the container without interfering with the placement of packages immediately adjacent to one another on a shelf.

These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the description of the current embodiment and the drawings.

Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components. Any reference to claim elements as “at least one of X, Y and Z” is meant to include any one of X, Y or Z individually, and any combination of X, Y and Z, for example, X, Y, Z; X, Y; X, Z; and Y, Z.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a package in accordance with an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the package.

FIG. 3 is an enlarged view of a portion of the package showing the tamper-evident tab.

FIG. 4 is an enlarged cross-sectional view of the package showing the lid and the base in the region of the tab.

FIG. 5 is an enlarged view similar to FIG. 3 with the tamper-evident tab broken away to provide access to the edge of the lid.

FIG. 6 is a perspective view of a package in accordance with an alternative embodiment of the present invention.

FIG. 7 is an exploded perspective view of the alternative package.

FIG. 8 is an enlarged view of a portion of the alternative package showing the tamper-evident tab.

FIG. 9 is an enlarged cross-sectional view of the alternative package showing the lid and the base in the region of the tab.

FIG. 10 is an enlarged view similar to FIG. 8 with the tamper-evident tab broken away to provide access to the edge of the lid.

FIG. 11 is an enlarged view of a portion of the base.

FIG. 12 is an enlarged view of a portion of the lid.

FIG. 13 is a top view of a plurality of packages arranged in an array.

DESCRIPTION OF THE CURRENT EMBODIMENT

A package having a tamper-evident tab arrangement in accordance with an embodiment of the present invention is shown in FIG. 1. The package 10 includes a base 12 and a lid 14. The base 12 is configured to receive items to be packaged and defines an opening 16 through which items can be placed into and removed from the package 10. The lid 14 is configured to close the opening 16 in the base 12. In the embodiment of FIG. 1, the base 12 includes a flange 26 and a rail 18 that extends around the opening 16. The lid 14 has a peripheral edge 20 having an outer shape that closely follows the inner shape of the rail 18. The edge 20 is shielded by the rail 18 to prevent a consumer from easily gripping the edge 20 to open the lid 14. The flange 26 includes a tamper-evident tab 38 that is movable to provide access to the peripheral edge 20 of the lid 14. The tamper-evident tab 38 may be connected to the flange 26 at opposite ends by lands 42 and 44. Land 42 may be breakable and land 44 may be a permanent tab that is intended to remain intact and function as a hinge about which the tamper-evident tab 38 is bent into the open position. The flange 26 may also include a fixed tab 40 disposed adjacent to the tamper-evident tab 38 opposite the breakable land 42. The fixed tab 40 may provide a gripping structure to assist in moving the tamper-evident tab 38 into the open position. In the embodiment of FIG. 1, the package 10 is generally cylindrical and the lid 14 can be placed on the base 12 in any orientation. In an alternative embodiment shown in FIG. 6, the package 210 may be rectangular and the tamper-evident tab arrangement may be positioned in a corner of the package 210. In this embodiment, the sidewall 24 of the base 12 may include a corner segment 26 e that is inset from the rectangular profile to provide space for an extended tamper-evident tab arrangement. As with package 10, the tamper-evident tab arrangement of package 210 may include a movable tamper-evident tab 238 and a fixed gripping tab 40. The lid 214 may include an extended horizontal portion that forms a lifting tab 253 that overlies the tamper-evident tab 238. In use, movement of the tamper-evident tab 238 into the open position exposes the lifting tab 253, thereby facilitating removal of the lid 214.

Although the present invention is described in connection with a package 10 intended for use in packaging food, such as fruits or vegetables, the present invention may be implemented in connection with packages intended for use in packaging other items. The size, shape and configuration of the package may vary from application to application, as desired. For example, the width, depth or shape of the base and/or lid may be varied to accommodate essentially any item or items to be packaged. The illustrated package 10 is intended to provide point-of-sale or point-of-purchase packaging for articles, but the present invention may be implemented in other types of packaging, if desired. It should also be noted that the present invention is illustrated in connection with a package 10 having a separate base 12 and lid 14. Alternatively, the present invention may be incorporated into a clamshell package in which the base and lid are joined along a living hinge.

Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the invention based on the orientation of the embodiments shown in the illustrations. The use of directional terms should not be interpreted to limit the invention to any specific orientation(s).

As noted above, the package of FIGS. 1-5 generally includes a base 12 and a lid 14 cooperatively define an internal space for receiving an item or items to be packaged. In the illustrated embodiment, the package 10 is generally cylindrical in external shape widening slightly toward the top. The shape of the package 10 may vary from application to application as desired. For example, the package may alternatively be generally rectangular in shape as shown in FIGS. 6-10 and described below. The lid 14 can be selectively installed on the base 12 to close the package 10. In this embodiment, the lid 14 is configured to snap onto the base 12. In the illustrated embodiment, the base 12 is configured to contain the bulk of the packaged item(s) and the lid 14 is configured primarily to close the open upper end of the base 12. In this embodiment, the base 12 is relatively deep and the lid 14 is relatively shallow, but the relative size and shape of the base 12 and lid 14 may vary from application to application. For example, the base 12 may alternatively be a relatively shallow tray and the lid 14 may form a relatively deep cover that contains the bulk of the packaged article(s).

Referring now to FIG. 2, the base 12 generally includes a bottom 22, a sidewall 24 and a flange 26. The bottom 22, sidewall 24 and flange 26 may be integrally thermoformed from a single sheet of stock material. In this embodiment, the bottom 22 is generally circular and may include contours, as desired. For example, the bottom of the base 12 may include a trough 28. The trough 28 may, among other things, provide a place to accumulate fluid, such as water that may run off of packaged fruits or vegetables. The trough 28 may also strengthen the base 12. The size, shape and configuration of the bottom 22 may vary from application to application, as desired. The trough 28 may be eliminated when not desired.

The sidewall 24 of this embodiment extends upwardly from the peripheral edge of the bottom 22. In this embodiment, the sidewall 24 corresponds in shape with the bottom 22. More specifically, the sidewall 24 of this embodiment is generally tubular having a slight outward taper from bottom to top. The size, shape and configuration of the sidewall 24 may vary from application to application, as desired. In the illustrated embodiment, a shoulder 30 is disposed toward the upper end of the sidewall 24. In this embodiment, the shoulder 30 is configured to provide a structure for snap-locking the lid 14 into place on the base 12. The shoulder 30 of this embodiment is an annular structure that extends entirely around the periphery of the package 10. In this embodiment, the shoulder 30 is continuous, but it may be discontinuous or otherwise extend through only one or more portions of the periphery of the package 10. As perhaps best shown in FIGS. 2 and 4, the base shoulder 30 may be formed to define an undercut 32 that allows the shoulder 30 to receive a corresponding shoulder 50 formed into the lid 14 (described in more detail below). The interaction of these shoulders 30 and 50 allows the lid 14 to be snap-locked onto the base 12. The size, shape and configuration of the shoulder 30, including undercut 32, may be varied to control the amount of force required to install the lid 14 on the base 12 and to separate the lid 14 from the base 12.

The flange 26 extends outwardly from the upper end of the sidewall 24 above shoulder 30 to form a peripheral lip extending around the top of base 12. In the illustrated embodiment, the flange 26 extends at an angle of just over ninety degrees from the sidewall 24 along a plane generally parallel to the bottom 22. The flange 26 includes a horizontal portion 27 that is configured to underlie the peripheral edge of the lid 14. The flange 26 of this embodiment generally includes a rail 34 that extends upwardly around the horizontal portion 27 of the flange 26. The rail 34 is configured to prevent access to the peripheral edge of the lid 14. To that end, the rail 34 includes an internal diameter that is only slightly greater than the external diameter of the lid 14. In this embodiment, the rail 34 is generally continuous except for a pair of relatively narrow breaks at opposite ends of the tamper-evident tab 36. The size, shape and configuration of the rail 34 may vary from application to application. The flange 26 includes a movable tamper-evident tab 36 that can be opened to provide access to a section of the peripheral edges of the lid 14 (as described in more detail below). In the illustrated embodiment, the tamper-evident tab 36 extends inwardly from the peripheral edge of the flange 26 through the rail 34 and into the horizontal portion 27 so that its movement into an open position provides access to a substantial portion of the peripheral edge of the lid 14. The tamper-evident tab 36 may extend into the horizontal portion 27 a distance sufficient to expose enough of the peripheral edge 20 to allow it to be firmly grasped between two fingers closing on the lid 14 from the top and bottom. The tamper-evident tab 36 is joined to the flange 26 by a series of lands 42 and 44. In the illustrated embodiment, there are lands 42 and 44 situated at opposite ends of the tamper-evident tab 36, but the number of lands may vary from application to application, as desired. In the embodiment of FIG. 2, land 42 is configured to break as the tamper-evident tab is opened, while land 44 is a permanent land that is configured to bend, but otherwise remain intact to function as a hinge while preventing the tamper-evident tab 36 from separating from the base 12. The tamper-evident tab 36 may include an extension 38 that protrudes outwardly to provide a structure for gripping the tamper-evident tab 36. The tamper-evident tab extension 38 may be positioned near the breakable end of the tamper-evident tab 36 so that opening force applied to the tamper-evident tab extension 38 is applied more directly to the breakable land 42. The flange 26 may also include a fixed tab 40 that is disposed adjacent to the breakable end of the tamper-evident tab 36. The fixed tab 40 may include an extension 41 that protrudes outwardly from the flange 26 to provide a structure that can be easily gripped by a user. In use, a user can break open the tamper-evident tab 36 by gripping the fixed tab extension 41 with one hand and the tramper evident movable tab 38 with the other hand, and then applying enough force to removable tab 28 to break lands 42 and move the tamper evident portion into an open position (See FIG. 5). The permanent land 44 may be substantially greater in width than the breakable land 42 so that substantially greater force is required to break the permanent land 44. For example, the permanent land 44 may be 1.5, 2 or 3 times the width of the breakable land 42. It is not, however, necessary for the permanent land 44 to be wider than the breakable land 42 for this functionality to occur. The structure of the tamper-evident tab 36 and fixed tab 40 may focus force on the breakable land 42 so that it breaks while the permanent land 44 does not. For example, positioning the extensions 38 and 41 on opposite sides of, and immediately adjacent to, the breakable land 42 results in focusing the force applied to the extensions 38 and 41 on the breakable land 42 and not on the permanent land 44. As a result, a user manipulating the tamper-evident tab 36 in the manner described will inherently rupture the breakable land 42 without breaking the permanent land 44, and will gain access to the edge of the lid 14 by bending the tamper-evident tab 36 about the permanent land 44 without any need to break the permanent land 44.

As noted above, the lid 14 is configured to be fitted onto the base 12 to close the package 10. In the illustrated embodiment, the lid 14 is generally circular and includes a peripheral edge 48 and a shoulder 50. The peripheral edge 48 is generally planar and is configured to lay against the horizontal portion of the flange 26 and terminate just inside the rail 34 (when the lid 14 is installed on the base 12). The spacing between the inside diameter of the rail 34 and the outside diameter of the peripheral edge 48 is small enough to make it difficult for a consumer to access the peripheral edge 48. The shoulder 50 of the lid 14 extends downwardly into the base 12 to interlock with the shoulder 30 of the base 12. The lid shoulder 50 is sized and shaped to fit tightly within the base shoulder 30, thereby providing a firm interlock (See FIG. 4). In the illustrated embodiment, the lid 14, shoulder 50 and peripheral edge 48 are circular and concentric, and are configured so that the lid 14 can be secured to the base 12 in essentially any rotational position. This facilitates packaging by eliminating the need to provide specific alignment between the lid 14 and the base 12 during installation of the lid 14. Although beneficial in some applications, the base 12 and/or lid 14 may be configured such that alignment between the base 12 and lid 14 is required. For example, the lid 14 and base 12 may include contours that ensure proper registration between the base 12 and the lid 14.

Operation of the tamper-evident arrangement of the present invention as implemented in package 10 will now be described with reference to FIGS. 3 and 5. When the lid 14 is installed on the base 12, the interlock between the lid shoulder 50 and the base shoulder 40 hold the lid 14 securely on the base 12. To remove the lid 14, it is generally beneficial to grip the peripheral edge 20 of the lid 14 and pull it upwardly away from the base 12. However, in the manufactured condition, the peripheral edge 20 of the lid 14 extends to within close proximity of the rail 34 making it difficult for a user to access the peripheral edge 20. To provide access to the peripheral edge 20, the tamper-evident tab 36 may be moved into the open position. The tamper-evident tab 36 extends into the horizontal portion of the flange 26 so that, once opened, a user can grip the peripheral edge 20 of the lid 14 between two fingers closing on the edge 20 from top and bottom. To break open the tamper-evident tab 36, a user can grip the fixed tab 40 with one hand and the movable tab 38 with the other hand, and then apply enough force to break land 42 and bend the tamper-evident tab 36 down along the permanent land 44 into an open position. Once the tamper-evident tab 36 is moved into the open position, it will not only expose a portion of the peripheral edge 20 of the lid 14, but also provide an obvious visual indication that the package 10 has been tampered with or opened.

An alternative embodiment of the present invention incorporated into a rectangular package 210 is shown in FIGS. 6-12. As with package 10, package 210 generally includes a base 212 and a lid 214 that have a tamper evident arrangement that can be moved into an open position to allow the lid 214 to be removed from the base 212 (See FIGS. 6 and 7). In this embodiment, the tamper evident arrangement is incorporated into a corner of the package 210 (See FIG. 8). For purposes of the disclosure, package 210 will be described with two digit reference numerals that generally correspond with those of package 10, except that they will be preceded with a “2” in the hundreds place. For example, with package 10, the base is identified by reference numeral 12 and with package 210, the base is identified by reference numeral 212.

Referring now to FIG. 7, the base 212 generally includes a rectangular bottom 222, a sidewall 224 and a flange 226. The bottom 222, sidewall 224 and flange 226 may be integrally thermoformed from a single sheet of stock material. In this embodiment, the bottom 222 is generally rectangular with front 225 a, rear 225 b, left 225 c and right 225 d peripheral edges. The illustrated bottom 222 has rounded corners and the four peripheral edges 225 a-d each follow a shallow outward curve. The bottom 222 may include internal contours, as desired. For example, the bottom 222 of the base 212 may include an internal trough 228 or other contours intended to strengthen the package 210 or to retain water or other fluids that might accumulate.

The sidewall 224 of the rectangular embodiment of FIGS. 5-12 extends upwardly from the peripheral edge of the bottom 222. In this embodiment, the sidewall 224 generally corresponds in shape with the bottom 222 having front 227 a, rear 227 b, left 227 c and right 227 d segments that each follow a shallow outward curve. In this embodiment, the tamper-evident tab arrangement is positioned in a corner of the package 210. To accommodate the tamper-evident tab arrangement, the sidewall 224 also includes a corner segment 227 e. The sidewall 224 segments of the illustrated embodiment each have a slight outward taper from bottom to top. The size, shape and configuration of the sidewall 224 may vary from application to application, as desired. In the illustrated embodiment, a shoulder 230 is disposed toward the upper end of the sidewall 224. In this embodiment, the shoulder 230 is configured to provide a structure for snap-locking the lid 214 into place on the base 212. The shoulder 230 of this embodiment is an annular structure that extends entirely around the periphery of the base 212 through the front, rear, left, right and corner segments. In this embodiment, the shoulder 230 is continuous, but it may be discontinuous or otherwise extend through only one or more portions of the periphery of the package 210. As perhaps best shown in FIG. 9, the shoulder 230 may be formed to define an undercut 232 that allows the shoulder 230 to receive a corresponding shoulder 250 in the lid 214 to snap-lock the lid 214 in place on the base 212. The size, shape and configuration of the shoulder 230, including undercut 232, may be varied to control the amount of force required to install the lid 214 on the base 212 and to separate the lid 214 from the base 212.

The package 210 may include additional aesthetic and functional features. For example, the front segment 227 a and rear segment 227 b may include features that interfit with corresponding features in the lid 214 to help prevent the front segment 227 a and rear segment 227 b from bowing out when the package 210 is loaded. In this embodiment, the front segment 227 a and rear segment 227 b each include a riser 229 that extends upwardly from the bottom 222 and terminates at its upper end in a T-shaped protrusion 231 having a central leg 233 and a cross leg 235 (See FIG. 11). The T-shaped protrusion 231 is configured to receive a pair of fingers 259 that extend downwardly from the lid 214 (See FIG. 12).

As with the flange 26 of package 10, the flange 226 of package 210 extends outwardly from the upper end of the sidewall 224 above shoulder 230 to form a peripheral lip extending around the top of base 212. In the illustrated embodiment, the flange 226 extends at an angle of just over ninety degrees from the sidewall 224 along a plane generally parallel to the bottom 222. In this embodiment, the flange 226 includes a rail 234 that extends upwardly to prevent access to the peripheral edge of the lid 214. To that end, the rail 234 includes an internal diameter that is only slightly greater than the external diameter of the lid 214. In this embodiment, the rail 234 is generally continuous except for a pair of relatively narrow breaks at opposite ends of the removable portion 236. The size, shape and configuration of the rail 234 may vary from application to application. As noted above, the package includes a tamper evident arrangement that is disposed in a corner of the package 210. In the illustrated embodiment, the tamper event arrangement is incorporated into the portion of the flange 226 extending from corner segment 227 e of the sidewall 223. As shown, the flange 226 includes a tamper-evident tab 236 that can be opened to provide access to a section of the peripheral edges of the lid 214. In the illustrated embodiment, the tamper-evident tab 236 includes a horizontal portion 227 that is configured to underlie the peripheral edge of the lid 214. The tamper evident tab 236 extends inwardly from the peripheral edge of the flange 226 through the rail 234 and into the horizontal portion 227 so that its movement into an open position provides access to a substantial portion of the peripheral edge 220 of the lid 214. The tamper-evident tab 236 may extend into the horizontal portion 227 a distance sufficient to expose enough of the peripheral edge 220 to allow it to be firmly grasped between two fingers closing on the lid 214 from the top and bottom. The tamper-evident tab 236 is joined to the flange 226 by a series of lands 242 and 244. In the illustrated embodiment, there are lands 242 and 244 situated at opposite ends of the tamper-evident tab 236, but the number of lands may vary from application to application, as desired. In the embodiment of FIG. 8, land 242 is configured to break as the tamper-evident tab is opened, while land 244 is configured to remain intact so that the tamper-evident tab 236 does not separate from the base 212. The tamper-evident tab 236 may include an extension 238 located near the breakable end of the tamper-evident tab 236. The tamper evident arrangement may also include a fixed tab 240 that is disposed adjacent to the breakable end of the tamper-evident tab 236. The fixed tab 240 may include an extension 241 that protrudes outwardly from the flange 226. As with package 10, a consumer can break open the tamper-evident tab 236 of package 210 by gripping the fixed tab extension 241 with one hand and the tamper-evident tab extension 240 with the other hand, and then applying enough force to break land 242 and bend, without breaking, the tamper-evident tab 236 about land 244 into an open position (See FIG. 10). The permanent land 244 may be substantially greater in width than the breakable land 242 so that substantially greater force is required to break the permanent land 244. For example, the permanent land 244 may be 1.5, 2 or 3 times the width of the breakable land 242. It is not, however, necessary for the permanent land 244 to be wider than the breakable land 242 for this functionality to occur. The structure of the tamper-evident tab 236 and fixed tab 240 may focus force on the breakable land 242 so that it breaks while the permanent land 244 does not. For example, positioning the extensions 238 and 241 on opposite sides of, and immediately adjacent to, the breakable land 242 results in focusing the force applied to the extensions 238 and 241 on the breakable land 242 and not on the permanent land 244. As a result, a user manipulating the tamper-evident tab 236 in the manner described will inherently rupture the breakable land 242 without breaking the permanent land 244, and will gain access to the edge of the lid 214 by bending the tamper-evident tab 236 about the permanent land 244 without any need to break the permanent land 244.

To provide a large tamper evident arrangement while still having efficient use of shelf space, the package 210 may be shaped so that the tamper evident arrangement substantially fills the space between adjacent packages 210 when placed immediately adjacent to one another on a shelf. More specifically, the shallow curves in the segments of the sidewall 224 cause the corners of the package 210 to be recessed or inset from the outermost extents of the package 210. This may be seen best in FIG. 13, which includes reference lines tangent to the front, rear, left and right peripheral edges of the flange 226. Further, the corner segment 226 e is inset even farther from the outermost extent to provide additional space for a tamper evident arrangement. As can be seen in FIG. 8, the tamper-evident tab 236 and fixed tab 240 extend beyond the outermost extents of the flange on adjacent sidewall segments. The dimensions of the tamper-evident tab 236 and fixed tab 240 are selected so that the tamper-evident tab 236 and fixed tab 240 substantially fill the available space when packages 210 are stacked in an array on a shelf.

The lid 214 of package 210 is configured to be fitted onto the base 212 to close the package 210. In the illustrated embodiment, the lid 214 is generally rectangular corresponding in small with the opening in the base 212. The lid 214 includes a peripheral edge 248 and a shoulder 250. The peripheral edge 248 is configured to terminate just inside the rail 234 so that it is difficult for a consumer to access the peripheral edge 48 when the lid 214 is installed. The shoulder 250 of the lid 214 extends downwardly into the base 212 to interlock with the shoulder 230 of the base 212. The lid shoulder 250 is sized and shaped to fit tightly within the base shoulder 230, thereby providing a firm interlock. The lid 250 includes a tamper evident corner 251 configured to interact with the tamper-evident tab arrangement. As perhaps best shown in FIG. 7, the shoulder 250 extends at an angle of approximately forth five degrees through the tamper evident corner 251. The peripheral marginal portion of the lid 214 disposed outwardly from the shoulder 250 forms an enlarged lifting tab 253. In the illustrated embodiment, the lifting tab 253 is generally planar and includes a peripheral edge with the same general size and shape and the other corners of the lid 214. The size, shape and configuration of the lifting tab 253 may be varied from application to application by varying the shoulder 250 and the peripheral marginal portion of the lid 214 outside the shoulder 250 in the tamper-evident corner 251.

The lid 214 may include additional contours, as desired, to provide strength or to implement aesthetic or functional features. For example, in the illustrate embodiment, the lid 214 includes a generally rectangular central planar cavity 257. The primary purpose of the cavity 257 is to receive a label (not shown). If desired, the cavity 257 may also be configured to closely receive the bottom of an above-stacked package 210 to provide nesting and improve the stability of stacked packages. Further, the lid 214 and base 212 may include mating features that help to prevent the front and rear segments of the sidewall 234 from bowing out. In this embodiment, the lid 214 includes a pair of small downwardly extending fingers 259 near the front and rear edges that mate with the T-shaped protrusions 231 in the front and rear segments of the sidewall 234 (See FIG. 12). When the lid 214 is installed on the base 212, each pair of fingers 259 straddles the central leg 233 of the corresponding T-shaped protrusion 231 in the space between the cross leg 235 and the sidewall 234.

Package 210 operates in a manner similar to that of package 10. When the lid 214 is installed on the base 212, the interlock between the lid shoulder 250 and the base shoulder 240 will hold the lid 214 securely on the base 212. To remove the lid 214, the tamper-evident tab 236 is moved into the open position to provide access to a portion of the peripheral edge 220 of the lid 214. To open the tamper-evident tab 236, a user grips the fixed tab extension 241 with one hand and the tamper-evident tab extension 238 with the other hand, and then applies enough force to break land 242 and bend the tamper-evident tab 236 down about the permanent land 244 into an open position. Once the tamper-evident tab 236 is moved into the open position, a portion of the peripheral edge 220 of the lid 214 will be exposed. The user can then remove the lid 214 by gripping the fixed tab 240 with one hand and the exposed portion of the lid 214 with the other. Once gripped firmly, the user can lift the lid 214 away from the base 212. To remove the lid 214, the user may grip the fixed tab extension 241 with one hand and the exposed portion of the peripheral edge 220 of the lid 214 with the other hand, and then lift with enough force to overcome the interlock between the lid shoulder and the base shoulder. Movement of the tamper-evident tab 236 into the open position also provides an obvious visual indication that the package 210 has been opened or at least tampered with.

The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described invention may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed embodiments include a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A thermoformed package comprising: a thermoformed lid having a shoulder and a peripheral edge extending outwardly from said shoulder; a thermoformed base having a bottom, a sidewall extending generally upwardly from said bottom and a flange extending outwardly from said sidewall around a periphery of said base, said sidewall including an annular shoulder extending at least partially around said base, said base shoulder configured to interlock with said lid shoulder when said lid is installed on said base; said flange including an annual upwardly extending rail, said rail having dimensions only slightly greater than those of said peripheral edge of said lid, whereby said rail impedes access to said peripheral edge of said lid when said lid is installed on said base; said flange including a fixed tab and a tamper-evident tab, said tamper-evident tab including a portion of said rail and underlying a significant portion of said peripheral edge of said lid when said lid is installed on said base, said tamper-evident tab joined to said flange at a first radial end by a first land and a second radial end by a second land, said tamper-evident tab including an extension adjacent to a first radial end, said fixed tab including an extension disposed adjacent said first radial end opposite said first land, said tamper-evident tab being selectively movable from a closed position to an open position by manually gripping said fixed tab extension and said tamper-evident tab extension and then breaking said first land and bending said tamper-evident tab out of alignment with said flange about said second land without breaking said second land such that said tamper-evident tab remains connected to said flange, movement of said tamper-evident tab into said open position exposing a portion of said peripheral edge of said lid, whereby said peripheral edge of said lid can be gripped by a user and used to lift said lid from said base.
 2. The thermoformed package of claim 1 wherein said annular shoulder and said peripheral edge are generally circular and generally concentric, whereby said lid can be installed on said base in any rotational position.
 3. The thermoformed package of claim 1 wherein said peripheral edge includes a generally planar portion, said tamper-evident tab include a generally planar portion underlying said planar portion of said lid, whereby movement of said tamper-evident tab to said open position exposed said planar portion of said lid.
 4. The thermoformed package of claim 1 wherein said tamper evident tab has an inward edge unconnected to said flange.
 5. The thermoformed package of claim 1 wherein said base and said lid are generally rectangular, said tamper-evident tab being disposed in a first corner of said base.
 6. The thermoformed package of claim 5 wherein said sidewall includes a first corner having an angled wall segment, said tamper-evident tab extending outwardly from said angled wall segment.
 7. The thermoformed package of claim 6 wherein said fixed tab extends outwardly from said angled wall segment adjacent to said tamper-evident tab.
 8. The thermoformed package of claim 1 wherein said sidewall include four primary wall segments extending in a generally rectangular arrangement and an additional corner wall segment extending between an adjacent two of said primary wall segments in a first corner of said base, said corner wall segment including a portion of said annular shoulder, said tamper-evident tab and said fixed tab extending outwardly from said corner wall segment.
 9. The thermoformed package of claim 8 wherein each of said primary wall segments is generally convex with an outermost extent of each primary wall segment being outwardly offset from opposed ends of said primary wall segment by a first distance, said tamper-evident tab extension and said fixed tab extension extending beyond said outermost extents of said primary wall segments adjacent to said corner wall segment by a distance that is approximately twice said first distance, whereby said tamper-evident tab and said fixed tab can extend beyond said outermost extents while allowing a plurality of the thermoformed packages to be arranged in an array without interference from said tamper-evident tab or said fixed tab.
 10. A thermoformed package comprising: a base defining an opening, said base including a flange extending around said opening, said flange including: an annular upwardly extending rail, a tamper-evident tab movable from a closed position to an open position, said tamper-evident tab including a portion of said rail and extending inwardly a substantial distance from said rail, said tamper-evident tab joined to said flange at a first radial end by a first land and a second radial end by a second land, said tamper-evident tab including an extension adjacent to said first radial end, and a fixed tab disposed adjacent to said tamper-evident tab, said fixed tab including an extension disposed adjacent said first radial end opposite said first land; and a lid releasably fitted to said base over said opening, said lid terminating in a peripheral edge adjacent to an inward side of said rail, whereby said rail impedes access to said peripheral edge when said lid is installed on said base; wherein said tamper-evident tab is selectively movable from a closed position to an open position by manually gripping said fixed tab extension and said tamper-evident tab extension and then breaking said first land and bending said tamper-evident tab out of alignment with said flange about said second land without breaking said second land such that said tamper-evident tab remains connected to said flange, movement of said tamper-evident tab into said open position exposing a portion of said peripheral edge of said lid, whereby said peripheral edge of said lid can be gripped by a user and used to lift said lid from said base.
 11. The thermoformed package of claim 10 wherein said lid includes an annular shoulder configured to interlock with a corresponding annular shoulder in said base, and said peripheral edge and said annular shoulder are generally circular and generally concentric, whereby said lid can be installed on said base in any rotational position.
 12. The thermoformed package of claim 10 wherein said peripheral edge includes a generally planar portion, said tamper-evident tab include a generally planar portion underlying said planar portion of said lid, whereby movement of said tamper-evident tab to said open position exposed said planar portion of said lid.
 13. The thermoformed package of claim 12 wherein said tamper evident tab has an inward edge unconnected to said flange.
 14. The thermoformed package of claim 10 wherein said base and said lid are generally rectangular, said tamper-evident tab being disposed in a first corner of said base.
 15. The thermoformed package of claim 14 wherein said base includes a sidewall, said sidewall including a first corner having an angled wall segment, said tamper-evident tab extending outwardly from said angled wall segment.
 16. The thermoformed package of claim 15 wherein said fixed tab extends outwardly from said angled wall segment adjacent to said tamper-evident tab.
 17. The thermoformed package of claim 10 wherein said base includes a sidewall, said sidewall including four primary wall segments extending in a generally rectangular arrangement and an additional corner wall segment extending between an adjacent two of said primary wall segments in a first corner of said base, said corner wall segment including a portion of said annular shoulder, said tamper-evident tab and said fixed tab extending outwardly from said corner wall segment.
 18. The thermoformed package of claim 17 wherein each of said primary wall segments is generally convex with an outermost extent of each primary wall segment being outwardly offset from opposed ends of said primary wall segment by a first distance, said tamper-evident tab extension and said fixed tab extension extending beyond said outermost extents of said primary wall segments adjacent to said corner wall segment by a distance that is approximately twice said first distance, whereby said tamper-evident tab and said fixed tab can extend beyond said outermost extents while allowing a plurality of the thermoformed packages to be arranged in an array without interference from said tamper-evident tab or said fixed tab.
 19. A tamper-evident food package comprising: top and bottom parts capable of being selectively interlocked to close the package, said top and bottom parts shaped to cooperatively define an article-receiving space when interlocked, said bottom part including a circumferential flange with a rim extending around said flange adjacent to an outer edge of said flange, said top part including a peripheral edge terminating inwardly of said rim, whereby access to said peripheral edge is impeded by said rim; said flange including a tamper-evident tab movable between a closed position and an open position, said tamper-evident having a first radial end joined to said flange by a breakable land and a second radial end joined to said flange by a permanent land, said tamper-evident tab having an extension extending outwardly from said tamper-evident tab adjacent to said breakable land and remote from said permanent land, said tamper evident tab including a portion of said rim, whereby movement of said tamper-evident tab moves said portion of said rim away from said top part to expose a portion of said peripheral edge; said flange further including a fixed tab disposed adjacent to said breakable land opposite said tamper-evident tab, said fixed tab including an extension extending outwardly from said flange, whereby a user can remove said top part from said bottom part by gripping said fixed tab with one hand, gripping said tamper-evident tab extension with the other hand and applying force in such a way as to first break said breakable land and second bend said tamper-evident tab away from its closed position about said permanent land without breaking said permanent land such that said tamper-evident tab remains connected to said flange. 